At present, as shown in FIG. 1, an OLED pixel driving circuit generally contains a transistor T11, a transistor T12, a storage capacitor C11 and various drive signals for driving the OLED. A specific circuit connection is shown in FIG. 1. A working process of the pixel driving circuit comprises stages as follows.
In a signal write-in stage, in the case that a scan signal Scan is at a high-level, the transistor T12 is switched on, a data signal Data is input to a gate electrode of the transistor T11 through the transistor T12, hence the transistor T11 is switched on and a capacitance C11 is charged.
In a light emitting stage, the scan signal Scan is turned to be at a low-level, the transistor T12 is switched off, and discharging by the capacitance C11 enables the transistor T11 to be still in an on state. A power supply voltage PVDD continuously provides the OLED with a voltage until a next stage comes. The above cycle is repeated.
However, due to a limitation of a process level, during a manufacture of a transistor circuit of an OLED display, a drive current of the OLED display deviates and a panel displays abnormally due to a threshold voltage exists for a driving transistor.